Gelation is the analytical signal used for the qualitative and quantitative detection of lipopolysaccharides. Bacterial endotoxins are lipopolysaccharides (LPS) located exclusively on the outer membrane of gram-negative bacteria; Their presence in injectable pharmaceutical products may be associated with problems during production, there are established endotoxin limits for this type of product. When the reagent is faced with solutions containing endotoxins, it produces gelling.
Explanation:
The LAL (Limulus Amebocyte Lysate) test is used to detect and quantify endotoxins associated with gram-negative bacteria. It is based on the amebocytes from the blood of the Limulus polifemus crab gel in the presence of minimal concentrations of endotoxin (ng / ml of blood ). It is positive in 60% of bacilli due to gram-negative enteric bacilli. The presence of endotoxins is determined by the formation of an insoluble gel or clot. The reaction requires the presence of divalent cations. The speed of the reaction depends on the endotoxin concentration, the pH and the temperature. The lysate contains a cascade enzyme system that is progressively activated in the presence of endotoxins. As a final result, the coagulable protein (coagulogen) is transformed into a gel (coagulin), which is the basis of the tube gel method.
